:: ASC :: Amateur Seismic Centre :: ASC :: Amateur Seismic Centre

:: ASC :: Amateur Seismic Centre

Website Guide   Home Recent Earthquakes 2004 M9.1 Sumatra-Andaman

About Us | Quake Alerts | Search

Recent Earthquakes
Felt An Earthquake?

Historical Intensity Maps
South Asia Seismicity
Great Earthquakes
Tsunamis & Seiches
GSHAP Hazard Maps
Seismology Links
Be Earthquake Safe!






M9.1 Sumatra-Andaman Earthquake & Tsunami, 2004


26 December 2004


North of Batunazerah, Aceh


00:58:50 UTC (06:28:50 IST)


3.298 N (NEIC)


95.778 E (NEIC)


10 kms (IMD)


Mw 9.1 (see below), 9.0 (HRV)

Additional Info


Map Disclaimer

A "very great" earthquake struck the North Indian Ocean & the Bay of Bengal at 00:58 UTC on 26 December 2004. The earthquake began near the island of Simuelue off the west coast of Sumatra and ruptured a 1,500-kilometre section of the boundary between the Indian Plate & the Burmese Microplate. Shaking from the earthquake was felt many parts of south Asia and Indo-China. A devastating Indian Ocean-wide tsunami was generated by this earthquake causing heavy fatalities in many countries surrounding the Indian Ocean basin. This event is also referred to as the "Boxing Day Tsunami and/or Earthquake", "The Asian Tsunami and/or Earthquake and the "Indian Ocean Tsunami".

Amateur Video from Banda Aceh, Indonesia

2,30,210 people were are estimated to have been killed in the Indian Ocean-wide tsunami generated by this earthquake (from Wikipedia); 1,84,168 of these were confirmed and 45,752 were missing. The highest death toll was from Sumatra where 1,30,736 persons were confirmed dead. This was followed by Sri Lanka where 35,322 fatalities were confirmed. 12,504 deaths were confirmed in India, 5,395 in Thailand, 82 in the Maldives, 78 in Somalia, 69 in Malaysia, 61 in Myanmar, 10 in Tanzania, 3 in the Seyschelles, 2 in Bangladesh, 2 in South Africa, 2 in Yemen and 1 in Kenya. This makes it one of the worst earthquake disasters in the 20th century, second only to the 1976 Tangshan earthquake in China that claimed 2,42,000 lives. In terms of the tsunami, it is the deadliest in recorded history and overshadows the past tsunami disasters at Sanriku in Japan (1896) and Lisbon in Portugal (1755). At the time of this ocean-wide tsunami no tsunami warning systems existed in the Indian Ocean. At many, if not most locations, the sea receded several metres before the first waves hit and this was the first indication that a "tidal wave" had arrived. This was heeded at some locations such as in Thailand and on Teresa Island (Nicobar Islands) with people fleeing to higher ground while alerting others. But in almost all other locations people rushed forth to witness or photograph this strange phenomenon or to gather dozens of fish left stranded by the retreating waters; moves that were to prove fatal in most cases.

Magnitude | Earthquake Shaking | Aftershocks | Tsunami | Seiches & other phenomenon

The epicentre of this earthquake was 42 kms N of Batunazerah (Simuelue Island), Indonesia,
or 102 k
ilometres SSW of Meulaboh (Sumatra), Indonesia,
or 257 k
ilometres SSE of Banda Aceh (Sumatra), Indonesia,
or 324
kilometres W of Medan (Sumatra), Indonesia,
or 990
kilometres SSE of Port Blair (South Andaman Island), India,
or 1806
kilometres ESE of Colombo, Sri Lanka,
or 2028
kilometres SE of Chennai (Tamil Nadu), India,
or 2177
kilometres SE of Bhubaneswar (Orissa), India.

The magnitude of this earthquake was initially reported to be Mw=8.2 by the NEIC. However, as more information was available, this was revised upwards a few hours later to Mw=9.0 based on a Centroid Moment Tensor solution derived by the CMT Working Group at Harvard University. Other studies done on this earthquake have arrived upon magnitudes (Mw=9.0-9.3) in this range and the small differences in these are due to differing assumptions on fault geometry. The officially recognised magnitude for this event is Mw=9.1. This earthquake is the 3rd largest instrumented earthquake since 1900 and the strongest anywhere on the planet since the 1964 Mw=9.2 Prince William Sound earthquake in Alaska and the strongest during the instrumented era in seismology i.e. 1966 to present. The largest earthquakes in the 20th century was a Mw=9.5 that struck southern Chile in 1960. Also, based on the recorded tide gauge data a Tsunami magnitude (Mt) of 9.1 was calculated for this event.

Media/Press Note:
The magnitude of this earthquake should be reported/read as "magnitude 9.1" and printed as "M9.1". Please note that this magnitude is NOT Richter magnitude (ML) but is instead Moment Magnitude (Mw) and therefore MUST NOT be reported as "on the Richter Scale".

Top of Page

Earthquake Shaking Effects:

The earthquake was strongly felt in northern Sumatra and in the Indian Andaman & Nicobar Islands i.e. along the rupture. The strongest shaking was experienced on the island of Simuelue off the coast of Sumatra where people were reportedly thrown to the ground by the mainshock. On Sumatra itself, strong and damaging shaking was felt along the west coast at places such as Kembang Cot and Meulaboh that caused a few modern buildings to collapse. Further inland, landslides were triggered in the Barisan Mountains and some buildings were damaged at Takaptuan. In the larger cities of Medan and Banda Aceh the shaking had varied effects. In Medan, although the quake was frightening enough to send people running outdoors and to cracks some windows, the city fared much better than Banda Aceh where some newer modern high-rise buildings such as the Pante Pirak department store suffered various grades of damage. Northward, damage to buildings was reported from the Andaman & Nicobar Islands. In the Nicobar Islands, buildings were damaged on the islands of Car Nicobar, Katchall and Nancowry. At Campbell Bay on Great Nicobar Island though many of the low-rise buildings escaped with hairline cracks some newer buildings suffered non-structural damage. Liquefaction was observed on Car Nicobar Island. In the Andaman Islands, damage was similar as in Indonesia, with newer buildings suffering more damage as compared to older & low rise structures. In Port Blair, the earthquake began as a noticeable tremor that progressed into a strong shaking that made it difficult to remain standing.

Farther away, to the east the quake was felt in many parts of Malaysia, Singapore and Thailand. he tremor was also felt in Bangkok, Chiang Mai and other cities in Thailand. Several high-rise buildings were evacuated in Malaysia, including at Pinang and Port Klang. The shock was also felt at Alor Star and Pangkor. Residents of Singapore also felt the earthquake.

To the west, the quake was felt at several locations in peninsula India as well as in the Bengal. Minor damage was reported form Barisal, Chandpur Sadar and Chittagong in Bangladesh. Elsewhere in the country it was felt in most places including the capital, Dhaka and many people were woken up, some went outdoors. It was the strongest earthquake to shake Bangladesh since 1988. In India, the quake was distinctly felt along the east coast. In Tamil Nadu, people felt distinct tremors in most parts of Chennai as well as at Pondicherry & Tuticorin. The quake was also felt at Bhubaneswar and in towns in the Mahanadi delta in Orissa and many people left their homes and went outdoors. It was also felt at Mayurbhanj, Jajpur, Koraput and Sunabeda. Tremors were also reported from the coastal belt of Andhra Pradesh from Srikakulam to Chittoor as well as in the cities of Nellore, Vishakhapatnam and Vizianagaram. People in Vishakhapatnam ran out of their homes in panic, most notably in the East Point Colony, MVP Colony and Seethamanmadhara areas. Tremors were also felt in Kochi in Kerala and Bengalooru in Karnataka. A few buildings developed cracks at Bhubaneswar, Chennai and Vishakhapatnam but there were no reports of major damage from any parts of mainland India due to this earthquake. In West Bengal, the quake was also felt in Kolkata. Tremors were also felt at Dhanbad and the surrounding towns in Jharkhand. The earthquake was also felt in high-rise buildings at distant locations such as Ahmedabad in Gujarat and Mumbai in Maharashtra. Many places in Sri Lanka, such as Kandy also felt the tremors for a prolonged period.

Top of Page

Several powerful aftershocks have been reported from the region. Additional strong earthquakes were reported from the adjoining parts of the Andaman & Nicobar Islands within hours of this earthquake. Many of these earthquakes occurred in or near the main islands in this archipelago. 23 aftershocks with magnitude in excess of Mb=6.0 were recorded till 00:00 GMT on 09 January 2005. The strongest aftershock within a week of the mainshock was a Mw=7.2 event that occurred at 09:51 AM IST on 26 December. This was centred 81 kilometres SW of Pulo Kunji in Great Nicobar Island. The possibility of further aftershocks in this magnitude range cannot be ruled out. A total of 25 aftershocks of M6.0 or greater occurred up to 24 January 2005, spread over a region from Simuelue Island (off Sumatra, Indonesia) in the south to near Landfall Island (off North Andaman, India), in the north. These and other aftershocks clearly delineate a 1,000+ kilometre section of the plate boundary between the Indian Plate and the Burmese Micro-Plate that ruptured in the mainshock on 26 December 2004. Some of the larger aftershocks were strong enough to be felt as far as Chennai on the east coast of India, causing panic and minor damage.

Top of Page

Indian Ocean-wide Tsunami:

Download Full Animation: NOAA Simulation | USGS simulation

A major tsunami also struck the coast of Aceh province shortly after the earthquake and was reported from the towns of  Banda Aceh and Lhokseumawe. Heavy damage and fatalities are reported from Banda Aceh and other towns in the province of Aceh. Large sections of Banda Aceh were destroyed in the tsunami. Satellite photos show the true extent of the damage to the city, with large northern sections completely wiped out. The Indonesia army and police cordoned off these sections to survivors as they cleared away thousands of bodies. Many fishing villages and towns such as Calang and Meulaboh, along the west coast of Aceh province were almost completely washed away. People are believed to have watched the water recede and the ran to pick up fish left stranded on the seafloor while other rushed to take photographs. The waves that followed penetrated the coast to a great extent but in some places their force was arrested by high cliffs along the shore.

In Sri Lanka, a wave reported by the press as being 40-feet high struck the eastern and southern coast. Residents of Colombo sought refuge on higher ground in fear as coastal areas of the city were hit by the tsunami. Other affected areas include Batticaloa, Galle, Jaffna, Matara and Trincomalee to mention a few. A passenger train, the "Queen of the Sea" on its way from Colombo to Galle was swept away near Telwatte killing over a 1,000 people and other locals who clambered aboard hoping it would save their lives. Buses and cars were washed out to sea and numerous seaside communities like Hambantotte were heavily damaged. Here, as in Indonesia, people were puzzled by the recession of the water and rushed forward to view this rare phenomenon and were then caught by the ensuing waves.  People in Trincomalee are thought to have gathered "bag loads of colourful fish" before the tsunami made landfall.

Many parts of the Thailand coast were badly affected and many popular tourist resorts like Khao Lak and Koh Phi Phi were badly hit. Thousands of tourists vacationing in the area were among the fatalities.  At one location, a shark was found in a hotel swimming pool once the water went down and two dolphins were also stranded in an inland pond.

In the Nicobar Islands, the tsunami causing widespread damage wiping out entire villages like Campbell Bay on Great Nicobar Island and Malacca on Car Nicobar Island. Waves nearly 3-storeys high, devastated the Indian Air Force base near Malacca. Satellite photographs detailed the extent of tidal inundation in these islands with some parts of Car Nicobar and Trinkat Islands permanently submerged. The worst affected in the Andaman & Nicobar chain is Katchall Island. Out of a total population of 5312, 303 were confirmed dead while 4354 were reported missing. The islands of Camorta, Car Nicobar and Trinkat also reported heavy human losses. In the Andaman Islands, considerable damage was caused by the tsunami to Port Blair, leaving ships perched atop docks and on roads. A large tidal surge also struck the entire eastern Indian seaboard. In the city of Chennai, the surge covered the entire breadth of Marina Beach. Cars and boats were carried away by the torrent. Local television stations showed panic stricken people fleeing in ankle-deep water that flooded roads along the Marina. City landmarks like the Ashtalakshmi Temple and the Santhome Church were also flooded. The worst affected region in Tamil Nadu was the port city of Nagapattinam, where entire neighbourhoods were inundated. Many pilgrims living around the Shrine of Our Lady of HeTITLEh at Vellankani drowned. Damage was also reported from Cuddalore, Pondicherry and Kanyakumari. Hundreds of tourists were trapped at the Vivekananda Memorial at Kanyakumari for several hours before being rescued. Further north in Andhra Pradesh, tsunami damage was reported from Nellore, Machlipatinam and Vishakhapatnam to name a few. Many people gathered at a beach near Machlipatinam for religion ceremonies were swept away. Parts of Vishakhapatnam were flooded causing panic among the citizens. Tidal surges caused damage and fatalities parts of coastal Kerala, the worst being in Kollam. Tidal surges were also reported from Mangalore and Suratkal in Karnataka and all along the Goa coast including the city of Vasco. Minor damage was reported from the coast of Maharashtra, most notably in the region of Ratnagiri and Sindhudurg areas where coastal flooding and strong currents swept away boats and inundated a few coastal roads and houses. Noticeable but less energetic surges were also experienced in Mumbai. Waves were also reported from Orissa and West Bengal but did not cause any damage. Eyewitnesses also stated that the sea first receded leaving the sea bed exposed for a few moments, during which children and adults alike rushed to gather fish left stranded.

The tsunami struck the Maldives killing many people and submerging many buildings in the capital, Male. The tsunami also struck Malaysia. Tsunami activity was also reported from Burma where many buildings and bridges were damaged in the town of Kawthaung as well as elsewhere along the coast.

The Australian Cocos Islands were also hit by a half metre tsunami and the coast of Western Australia experienced significant but non-destructive tsunami activity. Surges inundated coastal areas of Oman and a few people were injured in 5-metre waves that hit the Maharah region. Tsunami activity was also reported from East Africa. Tsunamis capsized boats in the Puntland region of Somalia and many fishermen were washed away. Further south in the Seychelles, fatalities were reported and the town of Mahe was reportedly flooded. In Kenya, one person was killed and many missing in Malindi and beaches were closed in Mombasa. Rodrigues Island and beaches on north Mauritius were flooded. The French administered, Reunion Island,  also boats in harbours sustained some damage. In Zanzibar near Tanzania, hotel guests were evacuated to higher ground. A half a metre wave was also recorded a Port Elizabeth in South Africa. Other locations such as Durban Harbour also recorded unusually strong currents. More than 1200 people were left homeless by the waves on the east coast of Madagascar. Tide gauges in countries around the Pacific rim also recorded minor wave activity. Such activity was recorded as far as Alaska, Hawaii and San Diego in the United States, Callao and Inquique in Chile and as well as New Zealand, Fiji, Vanuatu and American Samoa. In Mexico, 8-foot waves were reported at Manzanillo.

Top of Page

Seismic Seiches & Other Phenomenon:

This earthquake also caused energetic seismic seiches in water bodies in Assam, Jharkhand, Maharashtra, Manipur, Orissa and West Bengal. In Kolkata, residents of Behala in the south-eastern part of the city describe vigorous seiches in ponds in the area. Seismic seiches were also seen in other parts of Kolkata and also in Balasore in neighbouring Orissa. One person drowned in a pond as a result of a seiche in Nadia, West Bengal. Television news reports also said such instances were common in Bhubaneswar, Balasore, Puri and other towns in Orissa. Press reports from Jharkhand also spoke of similar occurrences in Dhanbad and Rajganj. Similar phenomena were observed throughout Bangladesh and at the Maipokhari Lake in eastern Nepal as well as from water bodies in northern Thailand. A seismic seiche was also reported from ponds in the Ganeshpuri temple and from Gorai in Mumbai in Maharashtra. Such seiches were reported from the almost same region in the last great Mw=8.5-8.7 earthquake in Sumatra in 1861.

Eruptions of natural gas that ignited along with eruptions of mud volcanoes were reported from locations along Burma's Arakan coast and also in Sandoway. A mud volcano, Barren 1, erupted on the uninhabited Baratang Island in the Andamans. This must not be confused with the very different, Barren Island volcano.
Some press reports also claimed that both, the Barren Island and the Narcondam volcanoes were erupting but these have since been proved to be baseless.

Top of Page

01) International Seismological Centre (ISC), London.
02) National Earthquake Information Centre (NEIC), Golden, USA.
Harvard Centroid Moment Tensor Solution (HRV), Harvard, USA.
04) Macroseismic information has been compiled by the ASC from reports by local media and local NGO personnel.

Page Citation
Information on this page may be reproduced in print or electronically but it is requested that a citation be given to this website in the form of a link i.e. "www.asc-india.org".

Map Disclaimer
International boundaries of India (especially Arunachal Pradesh, Jammu & Kashmir, Himachal Pradesh and Uttarakhand) on the displayed map are from Google Maps. These do not conform to the external boundaries of India recognized by the Survey of India. That they are displayed on this page via Google Maps, is only for display purposes and this should not be misinterpreted as an endorsement of these boundaries by the Amateur Seismic Centre (ASC).

Page Updated: 22 Feb 2008 | Website Disclaimer

Amateur Seismic Centre, Pune,